The Cammell Laird (CL) yard of British Shipbuilders (BS) last month successfully completed its first full-scale "extrusion" of a finished hull from its new 32m pounds sterling covered construction hall. A Type 42 destroyer weighing 2500 tonnes was eased down a length of 115 metres, at a rate of eight inches per minute, with the use of a technique that the yard claims is unique for its delicate balance between the friction of the hull on the slipway and the ease of movement. The article describes the technique which involves the use of US-made hydraulic rams to provide a maximum thrust of 556 tonnes per pair served by a common control position where a 100hp motor powers a 5000psi pump. The same system also serves the gripping mechanism which, although massive and completely fail-safe, is in effect unnecessary as a safety device in that the friction ratio on the slipway is 4:1 and a positive push is required from the rams for the ship to move. Extensive research into the most suitable material for the sliding interface led to the adoption of high-density polythene pads, mounted on timber blocks which slide on continuous high-tensile steel capping plate. Most of the weight of the hull is supported on the centreway, on which guide bars are mounted for the plastic pads: the 3ft-long strokes of the rams are transmitted to the hull through the heavy steel sliding members which rest entirely on these pads. The rams themselves are held on to the capping plate by friction grippers along the edge and during tests it was found that neither the pushing or restraining mechanisms were affected by river silt or hydraulic oil spilt deliberately onto the capping plate.

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  • Corporate Authors:

    Seatrade Publications Limited

    Fairfax House
    Colchester CO1 1RJ, Essex,   England 
  • Publication Date: 1980-8

Media Info

  • Pagination: p. 83
  • Serial:
    • Seatrade
    • Volume: 10
    • Issue Number: 8
    • Publisher: Seatrade Publications, Limited
    • ISSN: 0037-0428

Subject/Index Terms

Filing Info

  • Accession Number: 00319907
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 19 1980 12:00AM